Human renal kallikrein with a specific activity 2.5 times that found for hollow fiber concentrates of urine can be recovered in about 95% recovery by DEAE-cellulose batch adsorption of 120-liter lots of urine. In preliminary studies with 40% pure renal prokallikrein no evidence of an activation peptide was seen by high performance liquid chromatography (HPLC) after activation by catalytic amounts of trypsin. Thin-lay chromatography (TLC) of a dansylated, then acid-hydrolyzed incubation mixture of prokallikrein and trypsin revealed fluorescent spots for dansyl (Dns)-epsilon-lysine, Dns-glutamic or -aspartic, and Dns-isoleucine, -leucine, or -valine. Immunofixation of human plasma kininogens on electroblot transfers from alkaline polyacrylamide gels after electrophoresis of fresh samples of plasma revealed antigen patterns very similar to the stained protein band patterns previously obtained with kininogens purified by immunoaffinity chromatography